Re: Hadrosaur nesting strategy...(was Re: The Life of Birds- Pa

[Danvarner@aol.com]

In a message dated 7/28/99 9:01:54 AM Pacific Daylight Time, 
larryf@capital.net writes:

<< 
 It was suggested to me (offlist) that more abundance of food was the reason
 for bird migration. I thought food was always much more abundant in the
 tropics, and therefore the ability to brood in a colder enviorn as
 protection from cold-blooded predators would be the determining factor in
 bird migration.  >>

  But this was the Mesozoic. The arctic was not cold at all in summer. Nor 
the Antarctic in the austral summers. Migration is much about following the 
sun and it's attendant productivity. Back in the Age of Dinosaurs the warm 
polar regions of this planet must have run riot with life under a sun that 
would barely set for months at a time. Envisioning the long and dark but 
temperate polar winters becomes more difficult and interesting. This is where 
Mesozoic Earth becomes an unfamiliar planet indeed (do I sound enough like 
Attenborough?). As for predators--they can never be escaped. Mosquitoes and 
biting flies probably served out their apprenticeships on dinosaur hatchlings 
in the Cretaceous high latitudes.
  Once again I'd like to recommend _Travels and Traditions of Waterfowl_ by 
H.Albert Hochbaum, U of Minnesoa Press for a beautifully illustrated book on 
the topic of migration in ducks and geese. Dan Varner.